Automated institutional and industrial ware-washing machines are generally configured with a single wash tank for maintaining a readily available supply of a cleaning solution for use in the machine. During normal usage at least a portion of the cleaning solution is periodically discarded in order to keep the remaining cleaning solution as clean as possible. Fresh water or clean recycled water is than added to the wash tank to maintain an appropriate liquid level. Addition of the fresh water dilutes the concentration of detergent in the cleaning solution. To maintain the cleaning solution at the most efficient detergent concentration, a measured amount of a concentrated detergent solution is periodically added to the wash tank by an auxiliary detergent dispenser to form a cleaning solution of the desired strength.
The above referenced detergent dispensers are typically designed to automatic or semi-automatic operation. Automatic dispensers are preferred becuase they (i) eliminate the need for constant operator attention, (ii) minimize operator error due to misjudgment in timing or amount of cleaning composition to be added, and (iii) provide greater accuracy in maintaining the optimum concentration of cleaning composition in the wash tank.
One such automatic dispenser is designed to dispense a solid cast detergent by spraying water onto an exposed surface of the solid block of detergent to form a concentrated detergent solution which is directed to the wash tank of the washing machine. Such dispensers are disclosed in commonly owned U.S. Pat. Nos. 4,426,362, 4,569,780, and 4,569,781, and commonly owned co-pending U.S. application Ser. Nos. 796,017, 817,399 and 817,750.
Utilization of such auxiliary detergent dispensers requires the availability of a solid cast dissolvable detergent. Two methods of manufacturing such detergent blocks are disclosed in commonly owned U.S. Pat. Nos. 4,569,780 and 4,569,781 issued to Fernholz et al, and commonly owned U.S. patent application Ser. No. 663,473 now U.S. Pat. No. 4,595,520. Fernholz discloses a method for the casting of a homogeneous solid detergent composition comprising the steps of (i) heating a 40-75 wt-% aqueous solution of an alkali metal hydroxide, (ii) distributing about 15 to 40 parts by weight of an alkaline hydratable chemical into the solution to form a homogeneous mixture, (iii) pouring the homogeneous mixture into a receptacle, and (iv) allowing the mixture to solidify and form a homogeneous, solid cast detergent composition. Ser. No. 664,473 discloses a method for the casting of a homogeneous solid deterent composition comprising the steps of (i) forming an aqueous emulsion of an alkaline compound, a hardness sequestering condensed phosphate, a hectorite clay and a hydratable solidifying agent, (ii) heating the emulsion to a temperature sufficient to hydrate the solidifying agent, and (iii) cooling the emulsion to form a homogeneous, solid cast detergent composition.
While solid cast detergent compositions formed in accordance with Fernholz and Heile represent a substantial improvement over prior detergent compositions, the search for new and improved casting methods continues.
As a result of this search, I have discovered a novel method of forming a solid cast detergent composition.